Log reducer



LOG REDUCER 3 Sheets-Sheet 1 Filed April 30, 1965 INVENTOR G. H. TOMLINSON II July 11,1967

cs. H. TOMLIN$ON u 3,330,315

LOG REDUCER s Shets-Sheet 2 Filed April 30. 1965 INVENTOR G.H. TQMLINSUN E 1 y 1 1967 e. H. TOMLIINSON u I 3,330,315 I LOG REDUCER 3 Sheets-Sheet 5 Filed April :50, 1965 INVENT OR c. H. TOMLINSON II United States Patent 3,330,315 LGG REDUCER George H. Tomlinson H, Isle Perrot, Quebec, Canada,

assiguor to Dominion Tar & Chemical Company, Limited, Montreal, Quebec, Canada Filed Apr. 30, 1965, Ser. No. 452,968 il'iaims priority, application Canada, May 9, 1964, 902,457 13 Claims. (Cl. 144-176) ABSTRACT OF THE DISCLOSURE The device of the invention is for producing wafer chips particularly suitable for pulping, While permitting formation of cants. The device has a rotating head with a plurality of discrete wing knives, each knife having a main edge with an auxiliary edge projecting at an obtuse angle from one end of the main edge, arranged in a radially decreasing helical path about the head. The main edges extend in planes substantially perpendicular to the axis of rotation of the head and cut substantially parallel to the grain of the wood and the auxiliary edges cut at an angle across the grain. The main and auxiliary edges of each knife co-operate to separate a wafer from the wood.

The present invention is directed to a device for reducing logs to suitable shapes such as cents or the like while producing wafer-like wood chips suitable for pulping.

This invention relates to reducing logs to produce cants (or cut timbers having a square or rectangular crosssection) by removal of the excess wood from the log in the form of waferdype chips relatively accurately dimensioned in fibre direction and in thickness. The cants produced are finished and directly available for rough wood usage such as beams, railway ties, etc., or may be further cut, by a separate operation, and by conventional means into boards, dimensioned stock timber or the like. The chips, which are relatively undamaged when compared with chips produced by the conventional mu1ti-knife chipper used in the pulp and paper industry, are particularly suitable for the production of pulp. Thus, two premium products are simultaneously obtained, i.e., a squared timber and wafer-type chip, without losses in the form of sawdust and planer shavings inherent in conventional systems. With the present invention, it is, therefore, possible to vary the percentage of wood obtained in the two forms. For instance, if manufactured wood products are of special importance, only a minimum is converted to chips. On the other hand, when pulp production is of special importance, the log can be reduced to a relatively small standard dimensioned stock, or reduced completely to chips. The wafer-type chips so produced are of substantially uniform predetermined thickness and result in a pulp of greater strength than that obtained with conventional chips.

Prior to the .present invention, the procedures for reducing wood into shapes with simultaneous production of chips did not result in good quality wood particles for pulping. These prior art systems function in a manner similar to planers wherein the log is engaged with a cutting edge extending across the grain of the wood and revolving about an axis extending transversely to the grain. In such systems, chip length continuously changes, since the cutting edge moves through the wood with a scooping action and the angle of engagement between the cutting edge and the wood varies with rotation of the edge about its axis. Woodparticles produced in the above manner generally suffer fibre damage, are non-uniform and poorly shaped thus producing poorer quality pulp.

Applicants invention provides means for shaping a log while simultaneously producing wafer-like chips which are more uniform and generally of better quality than conventional chips.

The wafer-like chips of the present invention are cut with cutting blades mounted on a head rotating about an axis substantially perpendicular to the axis of the log to be reduced so as to produce on said log a plane face substantially parallel to the grain. The blades engage the log while the latter is made to travel in the direction of its length and the path of each blade on the log (i.e., the cut made by a blade) is in the form of an arc; this arcuate path will be the composite of the rotational movement of the blade and the longitudinal movement of the log. While the blade engages the wood along a line which is parallel to the grain or at a changing angle depending on the position on the arcuate path, the main surface of severance of a chip from the log is normally substantially parallel to the grain. The surface formed on the log by the last blade to cut is a semi-finished but not .a planed surface.

The blades are mounted in a substantially conical spiral pattern on the head, each blade having a main cutting edge and an auxiliary or wing cutting edge extending at an angle from one end of the main cutting edge. Each blade is mounted with its main cutting edge substantially in a radial plane (i.e., in a plane perpendicular to the axis of rotation of the head) and is oriented so that the main cutting edge lies preferably approximately along a radius. If the blade is oriented at too large an angle to the radius, the effective length of the cutting edge will be greatly reduced and the wings may cause some difficulties. The main cutting edge slices a chip while the auxiliary or wing edge severs across and at an angle to the grain to free the chip from the log.

A wafer-like chip produced in the above manner has two pairs of opposed cut faces and one pair of surfaces formed by splitting alorig the grain. The first pair of cut faces or the top and bottom faces are formed substantially parallel to the grain by the main cutting edges of adjacent knives in the knife pattern. The second pair of cut faces or the end faces are slightly curved and formed by wing edges cutting across and at an angle to the grain. The curvature of the end faces depends on the radius of rotation of the wing knives and also the speed of the log. The remaining two faces or the side faces, namely, those formed by splitting along the grain extend parallel to the grain of the wood.

It is the main object of the invention to provide a chipper that will continuously square a log while producing good quality wafer-likechips for pulping purposes.

A further object of the present invention is to provide a chip cutting and wood sizing head having built-in log controlling means. Applicants cutting head not only has a steadying means, but also has means to prevent overfeeding.

Broadly, the present invention comprises a head having a plurality of knives arranged in a predetermined pattern thereon, such that the knives will engage the log and produce a fiat face thereon by a single pass of the log, while simultaneously cutting wafer-like chips.

Further features, advantages and objects will be evident from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an end view of the wafer producing chipper shown in FIG. 2.

FIG. 2 is a schematic plan view of the chipper.

FIG. 3 illustrates an end view of a knife suitable for use with the present invention.

FIG. 4 is a partial cross section of a log cut by consecutive knives.

FIG. 5 is a partial sectional view illustrating the action of the knives.

: head 20 rotatable on its axis by any suitable drive means coupled to drive shaft 20A. A plurality of knives I, 2, 3, 4, 5, etc. extend from one surface of said head in what is herein termed a substantiallyconical spiral pattern. These knives are arranged in a-sequen c o n a path that spirals inwardly toward the axis of the head while simultaneously moving axially away from the drive end of said head thereby to form the desired pattern. 7

While the path of the knife arrangement is described as essentially a conical spiral, the actual path may or may 7 not be conical, depending on the knife arrangement, it

being usually preferred'to increase the number of knives per turn as the radius increases.

FIG. 1 is a side elevation of the cutting head illustrat- 7 ing the axial spacing between adjacent knives in the sequence. This spacing corresponds to the pre-set wood wafer thicknessfln the illustrated embodiment, the knives 4 D=number of degrees separating said one and said next knife P=the radial projection of. the effective cutting length are spaced from base surface 22 by. multiples of the chip thickness X as indicated at X, 2X, 3X, etc.

The knives are mounted with their main cutting edges in radial planes, so' that lel to the grain. I

To produce a smoother surface on the resulting shaped they will cut substantially paral- 7 log, it is' preferred to cut relatively thin chips with the last one or two knives, more specifically,'the last one or two 'cuts should only shave off chips of about ,5 inch or less in thickness to obtain a relatively smooth surface. This thickness van'es, for best results, depending on the species and condition of the wood being cut. Also,'a

' double winged knife, i.e., a knife' with wings extending at opposite ends of the maincutting edge, may be used'as the last knife in the sequence to aid in producing the smooth surface. Also, for some .woods, it may be desirable to mount the last knife at a slight angle from'the radial 'plane to facilitate producing thedesired surface.

The last knife in the sequence (in the illustrated embodiment, knife 16) of course, must be mounted on a radius:

larger than half the width of the surface produced *As above described, the knives are stepped axially and V radially of their head, with respect to adjacent knives in thesequence. The axial spacing has been described hereinabove and the radial spacing will now be described.

' of the -cutting edges 28 ofthe'wings26 of each of the V knives 1, 2, 3, etc. A running clearance is usually main tained for the. various surfaces 1B, 2B, 3B, etc., by pr'o- The change in radius between adjacent knives is a func-. 1

tion of the angular spacing between adjacent knives; the design length of the longest ,Wafer to be cut (i.e., the

maximum feed of 'the log per revolution for a single helical arrangement); the angle between the wing edge of the knife and themain cutting edge; and the chip thick ness. The actual radial spacing between knives 360 apart on a single spiralpattern is equal to the pre-set maximum chip length, plus the radial component'of the cut made b'y eachwing, multiplied by the number of wings in the 360". In other words, the change in radiusbetween one 7 knife and the next succeeding knife in the sequence may be defined by the following formula: V a

if LND where 'r =radius of one knife 'r =radius of the next succeeding knife in the sequence L=maximumpre-setchip length to be cut N='number of helical series 'of said auxiliaryrcutting edge The angular spacing between concentric. knives is preferably reduced as the radius increases. For symmetry, the peripheral spacing is sometimes held constant; thus, as the radius increases, the number of knives per turnof the spiral also increases.

The feed of the log is correlated so that'the log con- I tinuously advances one chip length for each rotation of r the cutting head, assuming the knives are arranged on'a single spiral pattern. If more than one sequence of knives. is used, 'e.g., a double or triple spiral, the log feedwill to the number of spiral be increased by a multiple equal arrangements used;

Referring again to FIGS, 1 and 2, the controlling'elements of applicants head will be'described. A' shown in FIGS. 1 and 2, a fiat surface trails each of the knives 1, 2 and 3, etc., as indicated at 1A, 2A, 3A, etc.

These faces 1A, 2A, 3A, etc., following each of the knives, serve to steady the log as it passes, the cutting head. The surfaces may terminate short of the subsequent knife in the series to provide a chip gullet or slotfI'n practice, the knives leading each surface will project very slightly above their respective trailing surfaces to allow.

a minor amount of clearance to thus holdpowerrequire- 'ments to a minimum. In operation, these surfaces 1A, 2A,

7 3A, etc., will be free of contact with the log beingproc essed, however, should the log tend to turn, out faces 34 (see FIG. 4) will engage some of the surfaces 1A,

2A, 3A, etc., and the log will be steadied by such engage-.

ment. Thus, the trailing surfaces 1A, 2A, 3A, etc., tend to stabilize the logbeing processed and ,also, thus aid in control of wafer thickness.

The surfaces 1B, 2B, 3B, etc., combine to' form a con- 7 ,7 I I tinuous essentially conical spiral surface (surfaces B, FIG. A 5) traced by the knife arrangement andthis combined surfaceB. prevents over'feeding. As illustrated, each of these surfaces 1B,- 2B, 3B, etc., follow and'are extensions jecting said edges. 28 very slightly beyond their respective surfaces 1B, 2B, 3B,:etc. In operatiomthe faces' lB,j2B," 3B, etc., normally clear the advancing log, however, if

there is a tendency for the log' to'advance too fast; this tendency is curbed by'engagement of the faces'36 of the. log with some of the faces 1B, 2B, 3B, etc;, on the head.

The log is usually fed radially to the head, and thus the knives initially engage the loglwith a component of movement in the opposite'direction to the feed and leave the log with a component of movement in the direction of the feed. Therefore, the relative movement longitudinally of the log between the log and any point on the head changes as'such point rotatesabout the axis of the a head. This means that a pointon the over-feed contour formed by the surfaces 1B, 2B, 3B, etc., approaches the log surface 36 most closely at one locationin its rotation.

This location is in the area where the radius of said point is in line with the longitudinalaxis of the feed, assuming the log is axially fed radially to the head.

Surfaces 1B, 2B, 3B, etc., may combine to form a' continuous surface as shown, or they may terminate short of the subsequent knife.

The knife arrangement may also be described in rela' 7 tion to the crests formed bythe juncture of the surfaces 1A and 13, 2A and 2B or 3A and 3B, etc. Each of-these crests trace a path receding toward the axis of the head along a line co-ordinated 'with the advance of the log per degree of rotation of the head, when the maximum or p're-.

set chip length is cut. This path extends from the juncture of the wing and 'main cutting edge of one knife to the point of minimum penetration of the wing of 2136 lQxt' j succeeding knife.

It is preferred to direct the log so that the centreline of the feed passes through the axis of the chipper as will be more fully explained hereinafter.

In operation, when the largest reduction is being made, knife 1 first engages the log and is followed by knives 2, 3, 4, etc., in that sequence. Usually, however, the first few knives will clear the log. These first few knives generally function to cut short stubs such as branches, etc., that may extend from the periphery of the log.

In FIG. 4, the first knife to contact the wood is knife 2. As schematically illustrated, the surfaces 36 carved on the log are shaped by the cutting edges 28 of the wings 26 of the various knives 1, 2, 3, etc. To produce such surfaces 36, the feed of the log is correlated with the path of the knife arrangement so that the cut made by the juncture of the wing edge 28 and main edge 24 of each preceding knife matches with the point of minimum penetration of the wing of each succeeding knife at the point in the travel of the knife where the knife moves perpendicular to the direction of feed (assuming the centre line of the feed passes through the axis of the cutting head). Surfaces 34 are produced by main cutting edges 24. The log is continuously advanced into the head and is continuously reduced by the succession of knives to produce a flat surface 34A corresponding to the surface cut by the last knife in the sequence (i.e., in the particular embodiment shown, knife 16).

Ribbons of wood are severed from the log 50 as schematically indicated at 52 in FIG. 6. These ribbons 52 pass through the head via the slots 54 provided for this purpose and break up into suitable chip widths. The chips 56 removed in the above manner may be collected with any suitable means and delivered to the pulp mill.

To cut a shorter chip length than the pre-set maximum design chip length of the device, it is only necessary to decrease the ratio of the rate of feed of the log to the angular velocity of the cutter head. When a maximum size chip length is not being cut, only that part of surfaces 1A, 2A, 3A, equivalent to the length of the chip out are in a position to aid in steadying the log.

The shapes of the wafer-like chips cut by the discrete knives in the sequence will not be completely uniform. This is due to several factors, namely, the change in angle of engagement of each knife with the log and the different radii at which each successive knife is mounted. However, this eflfect can be minimized by axially directing the log radially toward the axis of the head. Feeding the log in this direction has a second advantage since it reduces the diameter of head to a minimum to obtain a given reduction in size of a log.

It is preferred to limit the capacity of the device so that the width of the largest finished surface 34A to be produced is less than about the minimum diameter on which a knife is mounted.

In the illustrated embodiment, passages have been schematically illustrated passing through the head 20 to permit the chips to leave the cutting face of the head, however, any suitable system for removing chips from the device may be used.

While applicant has disclosed only a single head, it is evident that two heads can act on opposite sides of the log simultaneously to produce a cant in a single pass (see surfaces 34A and 34B, FIG. 4). Similarly, two pairs of heads can be mounted perpendicular to each other to act on the top, bottom and two sides of a log and form a square or rectangle in a single pass. Each of the heads would, of course, be mounted for axial movement to accommodate logs of different sizes.

Applicant has shown only 16 knives but it is evident that any number of knives may be used, depending on the size of the device and knife spacing. Also applicant has shown and described a single essentially conical spiral knife arrangement only, but as indicated, two or more spiral arrangements may be used.

I claim:

1. An apparatus for wafering or the like wherein logs are axially fed toward a cutting head rotating about an axis substantially perpendicular to the axis of said logs, said cutting head having a plurality of discrete knives mounted thereon in at least one radial decreasing helical sequence whereby said knives sequentially engage and reduce at least a portion of a log fed thereto into wafers, each said knife having a main cutting edge and an auxiliary cutting edge projecting out of the plane of said main edge at an obtuse angle from one end of said main cutting edge, each said rnain cutting edge being mounted on said head in a plane substantially perpendicular to the axis of said head with one end of said main cutting edge being at a greater radial distance from the axis than the other end, said auxiliary cutting edge projecting from said one end of said main cutting edge, the main and auxiliary cutting edges of any one of said knives co-operating when in engagement with said log to cut a wafer of parallelepipedic cross section therefrom, the change in radius between one knife and the next succeeding knife in one of said at least one sequence is defined 'by the formula:

where r =radius of said one knife r =radius of said next knife =maxirnumpre-set wafer length to be cut N =number of said helical sequences D=number of degreesseparating said one and said next knife P=the radial projection of the effective cutting length of said auxiliary cutting edge and wherein the axial spacing between said one and said next knife is equal to the thickness of wafer to be cut.

2. An apparatus as defined in claim 1 wherein control means are mounted on the said head trailing each said knife, said control means regulating movement of a log fed to said head.

3. An apparatus as defined in claim 2 wherein said control means comprises a surface trailing each said main cutting edge and extending in substantially the same radial plane as each main cutting edge immediately preceding said surface.

4. An apparatus as defined in claim 2 wherein said control means comprises a control surface for said at least one helical sequence extending about said head, said control surface adjacent each knife in a given one of said at least one helical sequence extending along substantially the same plane as each auxiliary cutting edge of each knife in said given one of said at least one helical sequence.

5. An apparatus as defined in claim 2 wherein said control means comprises a control surface for said at least one helical sequence extending about said head, said control surface, adjacent each knife in a given one of said at least one helical sequence extending along substantially the same plane as each said auxiliary cutting edge of each knife in said given one of said at least one helical sequence.

6. An apparatus as defined in claim 1 wherein the last knife in each said sequence has a second auxiliary cutting edge, projecting out of the plane of said main edge at an obtuse angle from the end of said main cutting edge remote from said auxiliary cutting edge.

7. An apparatus as defined in claim 1 wherein the last two knives in each of said sequences are pre-set to cut wafers less than inch thick while the remaining knives are pre-set to cut thicker wafers.

8. An apparatus for continuously reducing a log fed axially to a cutting head comprising a cutting head rotatable on an axis substantially perpendicular to the axis of said log, a plurality of discrete knives arranged along a radially retreating axially advancing path, each of said knives having a main cutting edge and an auxiliary cut- 'ting edge' projecting out ofthe plane of said knife and at an angle from one end of said main cutting edge, the

main and auxiliary cutting edges of any one of, said knives engaging said log-co-operating to cut wafers of parallel-' epipedic cross-section from said log, said knives being mounted on said head with each of said main cutting edgesextending in a plane substantially perpendicular to the axis of said head and'with said auxiliary edge at V the end of said main edge remote from'the axis of said head, a control surface trailing each said rnain cutting edge, each said control surface extending along substan- "tially the same plane as'its immediately precedinglmain cutting edge. a

9. An apparatus as defined in claim 8 wherein a second 7 control face extends about said head, said second control face being on substantially the same plane as the auxiliary cutting edges of each of said plurality of knives at different points along said control face, thereby to provide a spiral helical control surface.

I 10. An apparatus for continuously reducing wood to wafer-like wood particles while simultaneously shaping a log fed axially to a cutting head, said cutting head mounted to rotate about an axis substantially perpendicular to the axis of said log, an arrangement of knives of said and a secondary cutting'edge projecting out of the plane knife of'said knife andgat an angle from one, end ofsaidmain cutting edge, each said knife being mounted on said head with its main cutting edge extending substantially on a planeperpendicular to the axis of said head with said secondary cutting edge at the end of said main cutting edge remote from the axis of said head, a control surface trailing each main cutting. edge, each said control surface extending in substantially the same radial plane 1 as the main cutting edge of the immediately preceding 11. An apparatusas defined in claim 10 wherein a sec- 7 0nd control surface. is provided trailing said secondary cutting edge of each knife, at least-one section of each said second control surface extending in substantially the same plane as the immediately precedingsecondary cutting edge. 7 12. An apparatus as the wafers are cut. a a a 13. An apparatus as defined in claim 8 further comprising chip channels extending through said head to di rect wafers to the side of said head remote from where the wafers are cut. a

References Cited H UNITED STATES PATENTS 2,964,079 1271960 Johnson 144l76 3,011,535 12/1961 Andrusetal. a 3,216,470 11/1965 Nilsson 1 14-176X- WILLIAM W.DYER,JRdfrimaffExaminer; a

W. D. BRAY,AssistantExmi1irter. 5

defined in claim 1 further'com-j' prising chip channels extendingthrough said head to direct wafers to the side of said head remote from where 

1. AN APPARATUS FOR WAFERING OR THE LIKE WHEREIN LOGS ARE AXIALLY FED TOWARD A CUTTING HEAD ROTATING ABOUT AN AXIS SUBSTANTIALLY PERPENDICULAR TO THE AXIS OF SAID LOGS, SAID CUTTING HEAD HAVING A PLURALITY OF DISCRETE KNIVES MOUNTED THEREON IN AT LEAST ONE RADIAL DECREASING HELICAL SEQUENCE WHEREBY SAID KNIVES SEQUENTIALLY ENGAGE AND REDUCE AT LEAST A PORTION OF A LOG FED THERETO INTO WAFERS, EACH SAID KNIFE HAVING A MAIN CUTTING EDGE AND AN AUXILIARY CUTTING EDGE PROJECTING OUT OF THE PLANE OF SAID MAIN EDGE AT AN OBTUSE ANGLE FROM ONE END OF SAID MAIN CUTTING EDGE, EACH SAID MAIN CUTTING EDGE BEING MOUNTED ON SAID HEAD IN A PLANE SUBSTANTIALLY PERPENDICULAR TO THE AXIS OF SAID HEAD WITH ONE END OF SAID MAIN CUTTING EDGE BEING AT A GREATER RADIAL DISTANCE FROM THE AXIS THAN THE OTHER END, SAID AUXILIARY CUTTING EDGE PROJECTING FROM SAID ONE END OF SAID MAIN CUTTING EDGE, THE MAIN AND AUXILIARY CUTTING EDGES OF ANY ONE OF SAID KNIVES CO-OPERATING WHEN IN ENGAGEMENT WITH SAID LOG TO CUT A WAFER OF PARALLELEPIPEDIC CROSS SECTION THEREFROM, THE CHANGE IN RADIUS BETWEEN ONE KNIFE AND THE NEXT SUCCEEDING KNIFE IN ONE OF SAID AT LEAST ONE SEQUENCE IS DEFINED BY THE FORMULA: 